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Context A reliable measure of population size is fundamental to ecology and conservation but is often difficult to obtain. The woylie, Bettongia penicillata, provides an example where ‘getting the numbers right’ has important implications in verifying and quantifying the recent unexpected, rapid and substantial declines across much of its range. Initial estimates prompted a conservation-status upgrade for the species to Endangered by the Australian Government. The present paper constitutes the foundational paper addressing the first steps of a decline diagnosis framework intended to identify the causes of the recent declines. Aims To verify whether the declines in woylie trap-capture rates are representative of population change; better quantify the size of the largest woylie populations; and review what is understood about the ecology of the woylie and identify key knowledge gaps that may be relevant to identifying the causes of the recent declines. Methods Monitoring data from live-cage trapping (transects and grids), sandpads, woylie diggings and nest-density surveys and spotlighting were collated. Population measures derived from trapping data included capture rates, number of individuals, abundance estimates based on capture–mark–recapture modelling and density using spatially explicit capture–recapture models (SECR). Key results The declines in woylie trap-capture rates were verified as real population declines and corresponded closely with other measures of abundance derived from the same trapping data as well as with independent measures. A 95% decline occurred in the largest extant woylie populations (in the Upper Warren region, Western Australia) between 2002 and 2008. At a species level, woylies declined ~90% (1999–2006), from a peak of ~200 000 individuals in 1999. Conclusions An accurate formal conservation status is an important factor in promoting the conservation of a species. It is recommended that the woylie be considered for Critically Endangered status under the Australian EPBC Act. Implications Adequate and effective monitoring of species is critical to detecting and quantifying population changes in a timely manner. Having an accurate measure of population size can have a significant impact on the effectiveness of conservation and management efforts.

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Summary 1.Increasing concern over the sustainable management of forested landscapes and the extent of forest clearance world-wide has led to a growing interest in the impacts of logging and associated habitat disturbance on biodiversity. 2. We conducted an experimental study of the impact of clearfelling on birds of the karri Eucalyptus diversicolor forest in south-west Western Australia over a 17-year period, and a retrospective study of both clearfelled and naturally regenerated karri stands aged from 0 to 146 years. 3. One-third of species still had significantly reduced abundance 14 years after disturbance ceased, although all affected species made limited use of regenerating forest. 4. Multivariate analysis of changes in bird community structure showed that the effects of disturbance were still evident 14 years after clearfelling. Clearfelling may also have produced some temporary changes in community structure in adjacent unlogged forest. 5. Species richness and total abundance of birds declined by 58% and 96%, respectively, in the first year after clearfelling, and 14 years after logging were still 17% and 55% below levels in adjacent undisturbed forest. During this early successional phase both measures increased as a simple function of stand age. Species richness of regrowth reached that of old-growth at 30 -50 years and total abundance of all bird species in regrowth was similar to that of old-growth after approximately 70 years. 6. Several bird species offer potential as indicators of the ecological sustainability of karri forest management. These species nest in large hollows in standing live trees (two cockatoo species) or have been slow to recolonize immature regrowth karri forests (six species). 7. Post-hoc power analysis showed that even the long-term and intensive sampling employed in this study failed to detect declines in abundance of less than 80-90% for most bird species. For many uncommon species, trying to estimate changes in abundance is problematic and likely to require replication which is difficult to achieve in field situations where logged and unlogged forests are compared. Despite this, the present study identified some key impacts of forest clearfelling on bird communities, with implications both for the consequences of clearfelling of forests and the criteria for sustainable forest management.

Terrestrial vertebrate associations with silviculture and other factors were investigated as part of the FoRESTCHECK monitoring program in the jarrah (Euca/ytpus marginata) forests of south-west Western Australia. A total of 48 integrated monitoring grids form the basis of this study-sampled over five years (2001)(2002)(2003)(2004)(2005)(2006), across five ecosystem-defined regions (one sampled per year), each with replicates of two silvicultural treatments (shelterwood, gap release) and external reference forest (uncut forest or structurally mature forest that had not been harvested for timber for over 40 y). Terrestrial vertebrates were surveyed in spring and autumn using pitfall traps and wire cages. Forty-one terrestrial vertebrate taxa (8 frogs, 22 reptiles, 11 mammals) comprising 1165 captures were recorded.Fox (Vulpes vulpes) control had the strongest effect on terrestrial vertebrates, with baited areas supporting significantly more individuals (three-fold increase) than unbaited areas. The mammals Trichosurus vulpecu/a, Bettongia penicillata, Cercartetus concinnus and Dasyurus geoffroii, and the skink Tiliqua rugosa were particularly more abundant in fox-baited forest.Several terrestrial vertebrate community attributes (species accumulations by grids and number of individuals, dominance-diversity plots, overall community structure and overall abundance) differed little among the three treatments (i.e. two silvicultural, plus external reference forest). However, external reference grids had significantly lower species richness than the shelterwood grids and a significantly different community structure. These differences resulted from a greater prevalence within shelterwood of some species such as the reptiles Egernia napo/eonis, Menetia greyii, Ctenotus /abillardieri and Ramphotyph/ops australis. Forests that had never been harvested, a subset (8/15 grids) of the external reference treatment, had the lowest overall abundance, due largely to a confounding with fox control. The level of replication enabled differences between treatments of greater than 23% in species richness, and 37% in overall abundance, to be detected as statistically significant.Significant ecosystem/year differences were found. Differences in community structure between ecosystems/years approximated the geographic/bioclimatic relationships between the grids, with the distinction between southern jarrah communities (Jarrah South/200 1-02 and Jarrah Blackwood Plateau/2005-06) and the northern communities being particularly apparent. Time since last fire, live tree basal area, and the proportion of basal area removed by harvesting and silvicultural treatment were not correlated with vertebrate species richness, abundance or community structure. In comparison to the effect of fox control and regional/temporal variation, silvicultural treatment and the intensity of timber harvesting had minor impacts.Suggestions for the improvement of this and similar studies are discussed, with a particular focus on reducing residual variance and increasin...